The biggest bottlenecks on Day 2 of the sold-out Billboard Hot 100 Music Festival Sunday were on the small stretches of sidewalk between the stages.

Unlike most festivals where stages are separated by big fields, at Northwell Health at Jones Beach Theater they are so close that fans often choose to make a mad dash between sets, rushing from rockers Echosmith to pop sensations Jack & Jack, or from pop singer Camila Cabello to rapper Lil Yachty’s set.

It was the musician’s battle for attention come to life. And the most effective weapons were giving fans something new.

Marshmello, the new DJ who disguises his identity by wearing a plastic marshmallow on his head, had the main stage crowd going wild, even before he unleashed the huge pyrotechnics.

Echosmith introduced fans to songs from its upcoming “Inside a Dream” album, including the new single “Future Me,” which singer Sydney Sierota said the band had only played one other time in public. And DJ Khaled brought out Fat Joe as his special guest to celebrate the rapper’s birthday and to give him a chance to unveil his new single “So Excited.”

Khaled did throw a kink into an otherwise smooth festival, showing up 25 minutes late for his set, though he was onstage within five minutes of arriving. Though Khaled’s set was cut 20 minutes short, he did manage to play his big summer hits “I’m the One” and “Wild Thoughts.”

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The Hot 100 Music Festival is thriving on the idea of connecting young fans to new music and new artists.

And the addition of a fourth stage this year, the Heatseekers stage for New York area acts, certainly helped.

Brooklyn’s Surf Rock Is Dead made a great impression early on with their bouncier take on the early-aughts’ NYC sound of The Strokes and Interpol.

However, pretty much all of the Northwell Health at Jones Beach Theater grounds was transformed into a musical playground, from the impromptu dance club that popped up around the Hot 97 tent once the DJ started spinning old school hits like Bell Biv DeVoe’s “Poison” to the nonstop beach party at the Sun Stage.